Operative predictors of delirium after pulmonary thromboendarterectomy

Modification of pulmonary endarterectomy to prevent neurologic adverse events

PURPOSE

Neurologic adverse events (NAEs) are a major complication after pulmonary endarterectomy (PEA) performed under periods of deep hypothermic circulatory arrest (HCA) for chronic thromboembolic pulmonary hypertension. We modified the PEA strategy to prevent NAEs and evaluated the effectiveness of these modifications.

METHODS

We reviewed the surgical outcomes of 87 patients divided into the following three groups based on the surgical strategy used: group S (n = 49), periods of deep HCA with alpha-stat strategy; group M1 (n = 19), deep HCA with modifications of slower cooling and rewarming rates and the pH-stat strategy for cooling: and group M2 (n = 13), multiple short periods of moderate HCA.

RESULTS

PEA provided significant improvement of pulmonary hemodynamics in each group. Sixteen (29%) of the 49 group S patients suffered NAEs, associated with total circulatory arrest time (cutoff, 57 min) and Jamieson type I disease. The Group M1 and M2 patients did not suffer NAEs, although the group M1 patients had prolonged cardiopulmonary bypass (CPB) and more frequent respiratory failure.

CONCLUSIONS

NAEs were common after PEA performed under periods of deep HCA. The modified surgical strategy could decrease the risk of NAEs but increase the risk of respiratory failure. Multiple short periods of moderate HCA may be useful for patients at risk of NAEs.

Ramelteon for Prevention of Postoperative Delirium: A Randomized Controlled Trial in Patients Undergoing Elective Pulmonary Thromboendarterectomy

OBJECTIVES

To assess the efficacy of ramelteon in preventing delirium, an acute neuropsychiatric condition associated with increased morbidity and mortality, in the perioperative, ICU setting.

DESIGN

Parallel-arm, randomized, double-blinded, placebo-controlled trial.

SETTING

Academic medical center in La Jolla, California.

PATIENTS

Patients greater than or equal to 18 years undergoing elective pulmonary thromboendarterectomy.

INTERVENTIONS

Ramelteon 8 mg or matching placebo starting the night prior to surgery and for a maximum of six nights while in the ICU.

MEASUREMENTS AND MAIN RESULTS

Incident delirium was measured twice daily using the Confusion Assessment Method-ICU. The safety outcome was coma-free days assessed by the Richmond Agitation-Sedation Scale. One-hundred twenty participants were enrolled and analysis completed in 117. Delirium occurred in 22 of 58 patients allocated to placebo versus 19 of 59 allocated to ramelteon (relative risk, 0.8; 95% CI, 0.5-1.4; p = 0.516). Delirium duration, as assessed by the number of delirium-free days was also similar in both groups (placebo median 2 d [interquartile range, 2-3 d] vs ramelteon 3 d [2-5 d]; p = 0.181). Coma-free days was also similar between groups (placebo median 2 d [interquartile range, 1-3 d] vs ramelteon 3 d [2-4 d]; p = 0.210). We found no difference in ICU length of stay (median 4 d [interquartile range, 3-5 d] vs 4 d [3-6 d]; p = 0.349), or in-hospital mortality (four vs three deaths; relative risk ratio, 0.7; 95% CI, 0.2-3.2; p = 0.717), all placebo versus ramelteon, respectively.

CONCLUSIONS

Ramelteon 8 mg did not prevent postoperative delirium in patients admitted for elective cardiac surgery.

Pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension

Introduction. Pulmonary thromboendarterectomy (PTE) is a surgical procedure which is considered the only effective and potentially curative treatment for chronic thromboembolic pulmonary hypertension (CTEPH). CTEPH is a rare outcome from pulmonary emboli and, when left untreated, will result in right ventricular failure and death.

Methods. From June 1999 to November 2003, 40 of these procedures were performed in our institution. Emphasis is placed on multidisciplinarity and cooperation between different medical and surgical disciplines. Perfusion management consists of myocar-dial and cerebral protection, deep hypothermia with multiple periods of circulatory arrest, reperfusion at hypothermia, hemofiltration and cellsaving techniques.

Results. Hemodynamic improvement occurs immediately post operation. Mean pulmonary artery pressure decreased from 50±11 to 38±10 mmHg, pulmonary vascular resistance from 1246±482 to 515±294 dynes s/cm5 and cardiac index increased from 1.54±0.54 to 2.63±0.75 L/min per m2. Pump runs had an average duration of 187±29 min, circulatory arrest time was 29±11 min and crossclamp time 36±14 min. Extracorporeal membrane oxygenation can be an ultimate treatment for specific postoperative problems like persistent pulmonary hypertension and/or reperfusion pulmonary edema.

Chronic Thromboembolic Pulmonary Hypertension and Pulmonary Thromboendarterectomy

Chronic thromboembolic pulmonary hypertension results from incomplete resolution of a pulmonary embolus or from recurrent pulmonary emboli. Its incidence is underappreciated, and it is currently an undertreated phenomenon. Pulmonary thromboendarterectomy is currently the safest and most effective treatment for this condition. The surgery involves midline sternotomy, profound hypothermic circulatory arrest, and complete endarterectomy of the pulmonary vascular tree. Success depends on effective coordination of multiple medical teams, including pulmonary medicine, anesthesiology, and surgery. This review, based on the past 30 years of experience at University of California San Diego Medical Center, includes information about the clinical history, diagnostic workup, anesthesia, surgical approach, and postoperative care. Outcome data are discussed, as are avenues for future research.

Postoperative management of the patient undergoing pulmonary endarterectomy

The postoperative care of the patient undergoing pulmonary endarterectomy presents challenges that occur not only with other types of cardiac surgery but also with significant respiratory system changes related to alterations in pulmonary blood flow. Postoperative mortality associated with this procedure has declined substantially over the years as a consequence of improved evaluative procedures and selective surgical referral, advances in surgical technique, and an understanding of the unique postoperative complications that may occur. However, postoperative acute lung injury and residual pulmonary hypertension continue to represent major causes of mortality associated with this procedure and represent areas where additional investigative efforts are necessary. Here we describe the unique hemodynamic and respiratory changes that occur in the postoperative pulmonary endarterectomy patient and an evidence-based approach to their optimal management.

Pulmonary endarterectomy

Chronic thromboembolic pulmonary hypertension is a condition that is recognised in an increased percentage of patients. Pulmonary endarterectomy is recognised as being the only curative option for a subgroup of those patients, but anaesthesiologists and intensivists face many challenges in how they manage these patients perioperatively. Ultimately, it is the combination of skills in a multidisciplinary team that leads to a successful procedure and dramatically improves patient's quality of life and life expectancy.

Anaesthesia management for pulmonary endarterectomy

PURPOSE OF REVIEW

Options for the surgical treatment of chronic thromboembolic pulmonary hypertension are either lung transplantation or pulmonary endarterectomy. Pulmonary endarterectomy is considered permanently curative and the treatment of choice. The procedure dramatically improves functional status and provides an excellent immediate and long-term survival, much better than transplantation. Pulmonary endarterectomy, until recently performed in only a few highly specialized centres, is now spreading worldwide with good results. This review will focus on the understanding of the pathophysiology of the disease and on recent advances in assessment and treatment strategies.

RECENT FINDINGS

Recent data reinforce the thromboembolic nature of chronic thromboembolic pulmonary hypertension, and have shown that the disorder is more common than was thought and remains underdiagnosed. There has recently been a remarkable surge in the understanding of the mechanisms involved in the pathogenesis of pulmonary hypertension. Advances in diagnosis, surgical techniques, preoperative treatment, and perioperative management have improved the prognosis of this debilitating disease. New information about pretreatment and medical treatment with prostanoids and endothelin receptor antagonists is now available.

SUMMARY

Pulmonary endarterectomy can be successfully performed in selected centres using a multidisciplinary approach involving the specialities of surgery, pulmonary medicine, cardiology, radiology, anaesthesiology and critical care medicine. The largest risk factor remains the degree of operability related to a high pulmonary vascular resistance caused by permanent changes in the pulmonary vascular bed. Early operation is now recommended to prevent these irreversible changes. Further investigations are warranted to establish the role of new drugs in surgical patients with chronic thromboembolic pulmonary hypertension.

Arch reconstruction without circulatory arrest: scientific basis for continued use and application to patients with arch anomalies

Aortic arch hypoplasia is a common constituent of congenital heart disease. While repair of these lesions has been performed routinely during deep hypothermia and circulatory arrest, new approaches are emerging. One such approach, regional low-flow perfusion, will be described here. This technique exploits the anticipated modified Blalock-Taussig shunt as a perfusion conduit. With control of the brachiocephalic vessels and the descending thoracic aorta, circulatory support can be provided to the neonate with exposure identical to that obtained by circulatory arrest. While first applied to children undergoing the Norwood operation for hypoplastic left heart syndrome, this technique has recently been applied to children requiring complex arch surgery in the setting of biventricular repair. To date, 36 neonates requiring arch reconstruction (27 Norwood operations, 9 biventricular repairs) have been supported with regional low-flow perfusion. Thirty-day and hospital discharge survival has been 74% (20/27) for neonates undergoing Norwood operation, and 88% (8/9) for those undergoing biventricular repair. We will review the operative technique, methodologies, and clinical studies that led us to conclude that regional low-flow perfusion provides cerebral, as well as somatic, circulatory support to the neonate undergoing arch reconstruction.

Chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) should be differentiated from other etiologies of pulmonary hypertension since surgical intervention may be potentially curative. The presentation of this illness is nonspecific and may mimic other cardiopulmonary disease states. Without treatment, progressive pulmonary hypertension, right heart failure, and death will ensue. Echocardiography, lung ventilation-perfusion scan, right heart catheterization, and angiography are required for proper diagnosis and preoperative assessment. Definitive treatment requires surgical resection of thromboembolic material. The role of medical therapy remains to be defined.

Regional low-flow perfusion provides somatic circulatory support during neonatal aortic arch surgery

BACKGROUND

Regional low-flow perfusion has been shown to provide cerebral circulatory support during neonatal aortic arch operations. However, its ability to provide somatic circulatory support remains unknown.

METHODS

Fifteen neonates undergoing arch reconstruction with regional perfusion were studied. Three techniques were used to assess somatic perfusion: abdominal aortic blood pressure, quadriceps blood flow (near-infrared spectroscopy), and gastric tonometry.

RESULTS

Twelve patients required operation for hypoplastic left heart syndrome, and 3 required arch reconstruction with a biventricular repair. There was one death (7%). Abdominal aortic blood pressure was higher (12+/-3 mm Hg versus 0+/-0 mm Hg), and quadriceps blood volumes (5+/-24 versus -17+/-26) and oxygen saturations (57+/-25 versus 33+/-12) were greater during regional perfusion than during deep hypothermic circulatory arrest (p < 0.05). During rewarming, the arterial-gastric mucosal carbon dioxide tension difference was lower after circulatory arrest than after regional perfusion (-3.3+/-0.3 mm Hg versus 7.8+/-7.6 mm Hg, p < 0.05).

CONCLUSIONS

Regional low-flow perfusion provides somatic circulatory support during neonatal arch surgical procedures. Support of the subdiaphragmatic viscera should improve the ability of neonates to survive the postoperative period.

Regional low-flow perfusion provides cerebral circulatory support during neonatal aortic arch reconstruction

OBJECTIVE

Because of concerns regarding the effects of deep hypothermia and circulatory arrest on the neonatal brain, we have developed a technique of regional low-flow perfusion that provides cerebral circulatory support during neonatal aortic arch reconstruction.

METHODS

We studied the effects of regional low-flow perfusion on cerebral oxygen saturation and blood volume as measured by near-infrared spectroscopy in 6 neonates who underwent aortic arch reconstruction and compared these effects with 6 children who underwent cardiac repair with deep hypothermia and circulatory arrest.

RESULTS

All the children survived with no observed neurologic sequelae. Near-infrared spectroscopy documented significant decreases in both cerebral blood volume and oxygen saturations in children who underwent repair with deep hypothermia and circulatory arrest as compared with children with regional low-flow perfusion. Reacquisition of baseline cerebral blood volume and cerebral oxygen saturations were accomplished with a regional low-flow perfusion rate of 20 mL x kg(-1) x min(-1).

CONCLUSIONS

Regional low-flow perfusion is a safe and simple bypass management technique that provides cerebral circulatory support during neonatal aortic arch reconstruction. The reduction of deep hypothermia and circulatory arrest time required may reduce the risk of cognitive and psychomotor deficits.

Postoperative management of the patient undergoing pulmonary thromboendarterectomy

The postoperative course of the patient undergoing pulmonary thromboendarterectomy poses a unique series of challenges in terms of ventilatory care and hemodynamic management. Experience, cooperation, and interaction are necessary among the various disciplines providing care for these patients during the preoperative, operative, and postoperative phases of care. The purpose of this article is to share the approach necessary for the optimal postoperative care of the patient undergoing thromboendarterectomy, to present the theoretical justification for this care, and to delineate the areas of uncertainty that still exist.

Historical perspective: surgery for chronic thromboembolic disease

Obstruction of major pulmonary vessels with organized thromboemboli is a rare sequelae of acute pulmonary embolic disease. Depending on the extent and duration of vascular occlusion, patients experiencing this unusual disorder may develop significant pulmonary hypertension and cor pulmonale. If left untreated, the ultimate clinical outcome is right heart failure and death. Over the past several decades, the description of this clinical entity has evolved from an autopsy curiosity to a recognized cause of chronic pulmonary hypertension. Also, during this same time period, surgical capabilities have greatly advanced, providing these patients a potentially life-saving remedy for this debilitating form of pulmonary vascular disease. This article provides a historical perspective for our current understanding of major vessel chronic thromboembolic pulmonary hypertension as a distinct clinical disorder. It also chronicles the developments in surgical techniques that have made thromboendarterectomy of the pulmonary arterial bed a reality.

The evolution and the current state of the art of pulmonary thromboendarterectomy

Optimal reduction in pulmonary vascular resistance caused by chronic pulmonary embolism is obtained by bilateral pulmonary thromboendarterectomy with removal of occlusive material in all bronchopulmonary segmental arteries that are partially or completely obstructed. The most effective way to obtain this goal is the use of median sternotomy with cardiopulmonary bypass, deep hypothermia, and intermittent periods of circulatory arrest. During circulatory arrest, thromboendarterectomy is performed by specially designed dissectors that allow simultaneous dissection and removal of blood from the surgical field. The operative mortality rate for pulmonary thromboendarterectomy at the University of California, San Diego, between 1990 and 1998 was 9.2% in 1,049 patients.

Improved exposure of the pulmonary arteries for thromboendarterectomy

Pulmonary thromboendarterectomy is a surgical technique for treating pulmonary hypertension caused by unresolved pulmonary embolism. It has been recommended to perform this procedure under deep hypothermic circulatory arrest. Here we describe two technical modifications: (1) improved exposure to the right pulmonary artery by division of the superior caval vein and (2) thromboendarterectomy in normothermic cardiopulmonary bypass, with beating heart or electrically induced ventricular fibrillation. These modifications allow complete endarterectomy of both pulmonary arteries under normothermic conditions, thus avoiding hypothermic circulatory arrest, which results in short cardiopulmonary bypass times and reduces the morbidity and mortality of this procedure.

Writing disturbances: an indicator for postoperative delirium

OBJECTIVE

To study the writing ability pre- and postoperatively in patients undergoing major surgery.

METHOD

In an open study twenty-four consecutive patients undergoing thoracotomy for pulmonary malignancy were monitored for postoperative delirium throughout their stay in the hospital. The writing ability was tested on a preoperative day and on the third day after the operation. Main outcome measures were delirium according to the DSM-III-R criteria and writing ability assessed on items such as reluctance to write and motor-, spatial-, syntactical- and spelling disorders.

RESULTS

Five patients (21%) developed delirium according to the DSM-III-R criteria. The writing of all patients with delirium was severely impaired with features like reluctance to write, motor disability and spatial disturbances. No patient without delirium developed these disturbances.

CONCLUSIONS

These results suggest that testing of writing ability may be useful in the diagnosis of delirium. The Delirium Writing Test is proposed as a diagnostic tool.

Successful pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension associated with anticardiolipin antibodies: report of a case

Chronic pulmonary thromboembolism with pulmonary hypertension is a rare but most unique syndrome in the broad spectrum of pulmonary embolism. This report describes a successful pulmonary thromboendarterectomy performed for a totally occluded right pulmonary artery on a 43 year old man who presented with positive cardiolipin antibodies. The surgery was performed through a median sternotomy with cardiopulmonary bypass and intermittent periods of deep hypothermic circulatory arrest. We are convinced that this method allows for complete removal of the thrombotic obstruction and should be the procedure of choice for patients with very proximal obstruction of a pulmonary artery.

Hypoalbuminemia in delirium

The charts of 100 delirious patients seen by a psychiatric consultation service were reviewed. The most common chronic medical problems included diabetes and cardiovascular disease, while infections and trauma were the most common acute problems. The most frequent laboratory abnormality was hypoalbuminemia, appearing in 66% of those tested. Hypoalbuminemic patients were more likely to have a combination of medical problems, long hospital stays, and increased mortality, while patients with normal albumin were more likely to have drug toxicities and short hospital stays. While hypoalbuminemia develops because of many physiological processes, the data suggest that more attention should be paid to nutrition and serum transport capability in medical patients.

Dissectors for pulmonary thromboendarterectomy

Even with circulatory arrest during pulmonary thromboendarterectomy, continued back-bleeding obscures the operative field. This necessitates frequent interruptions of dissection to allow aspiration with a second instrument. Therefore, pulmonary thromboendarterectomy dissectors are described that allow simultaneous suction of blood from the operative field. Before the use of these dissectors, circulatory arrest time was 59 +/- 23 minutes in 124 consecutive patients. In the last 10 consecutive patients using these dissectors, the mean circulatory arrest time has been 52 +/- 22 minutes (p = not significant). It is anticipated that with a larger database, the ability to aspirate blood simultaneously during the dissecting process will result in a significant shortening of circulatory arrest time.

Pulmonary vascular steal in chronic thromboembolic pulmonary hypertension

After pulmonary thromboendarterectomy, performed for relief of chronic thromboembolic pulmonary hypertension, perfusion lung scans have frequently disclosed new perfusion defects in segments served by undissected pulmonary arteries. Our hypotheses were that these new postoperative defects occurred with great frequency and did not represent postoperative vessel occlusion. We retrospectively reviewed the preoperative and postoperative perfusion scans of 33 consecutive patients undergoing pulmonary thromboendarterectomy. New postoperative perfusion defects were noted in 23 of 33 patients. The incidence of new defects was increased tenfold in segments that had (1) normal preoperative angiographic findings, (2) normal preoperative radionuclide perfusion, and (3) not been entered at the time of surgery. Postoperative angiograms, available in 15 of 33 patients, documented the nonembolic, nonocclusive nature of the new perfusion scan defects. The most plausible alternate explanation for this previously undescribed finding is a redistribution of pulmonary arterial resistance induced by the thromboendarterectomy, namely, a pulmonary vascular "steal."

Technique of pulmonary thromboendarterectomy for chronic pulmonary embolism

Pulmonary embolism infrequently results in severe chronic pulmonary arterial obstruction. However, when it does, affected patients are significantly symptomatic and have shortened survival. Medical management has proven ineffective. In the majority of surgical reports, unilateral thoracotomy with distal pulmonary arteriotomies has been emphasized. The average operative mortality was 22%. In this article, we discuss various preoperative considerations and describe in detail a surgical approach using median sternotomy for bilateral pulmonary thromboendarterectomy with cardiopulmonary bypass, deep hypothermia and circulatory arrest. With this standardized approach in 103 consecutive patients from October 1, 1984, to September 20, 1988, the hospital mortality (death within 30 days or during hospitalization) has been 11.7%.